In general, a boot is held in place on a ski by means of a front and a rear binding. One of these bindings, most frequently the rear one, is equipped with means allowing adjustment of its longitudinal position, in order to permit use of the ski with boots of different lengths.
In some cases, the two bindings incorporate means designed to adjust their longitudinal position. This is the case for some rental bindings, which are intended for use with a broad range of boots having very different lengths. The longitudinal adjustment of the two bindings thus makes it possible to adapt the ski to a determinate boot length, and to bring the middle of the boot into substantial coincidence, with the middle of the ski.
Different devices are known which allow this adjustment of the longitudinal position of the front binding. For example, Patent No. FR 2 578 534 describes a front binding whose base moves along a slide-rail. The means allowing adjustment of the longitudinal position of the base incorporate, in the base, lateral teeth which cooperate with slots in the slide-rail and a kind of cam which forces the teeth to engage in the slots. A device of this same type is described in Patent Application No. FR 2 632 200.
These devices require a tool for achieving longitudinal adjustment. Moreover, the base of the binding is specifically intended for this application, i.e., it is specially configured for the purpose of longitudinal adjustment.
In addition, Patent Application No. EP 169 315 discloses an adjustment device designed to equip a front binding. This device comprises a control lever whose actuation controls the insertion of a rod in one of the slots in a slide-rail. As in the preceding case, the device requires a specific configuration of the binding, i.e., the entire binding must be designed and produced based on the existence of this equipment.
French Patent No. 2 284 347 discloses an adjustment device comprising three main parts which move longitudinally in relation to each other. This device comprises, first, a base plate attached to the ski. A support plate is guided on the central part of the base plate, whose position is determined by a mobile slider carried by the base plate. Finally, a guide plate is guided on the lateral wings of the base plate and moves in relation to the support and against the force exerted by return springs.
The disadvantage of this device lies in its complexity. Indeed, it comprises three parts which slide in relation to each other.
Furthermore, this device is not practical, since the slider is carried by the element attached to the ski. It is not possible to manipulate the slider and shift the binding simultaneously with one hand.
Finally, this device cannot be used for all bindings, in particular for front bindings. In effect, the return springs belonging to the guide plate do not prove useful for these bindings. The device is actually designed for rear bindings and is intended to receive only the body of the rear binding, not the binding in its entirety.